More than a million people in the U.S. have severely impaired vision. Their visual impairments are diverse and there is only limited understanding of how these impairments affect performance of daily tasks such as walking and reading. The NEI and several workshops sponsored by it have identified a need for research on the visual requirements of everyday tasks. We seek to determine what aspects of visual capacity can be measured in the laboratory to predict mobility performance. Partially and normally sighted subjects will participate. Normally sighted subjects will wear goggles which restrict vision in various ways (field restriction, contrast reduction, and spatial-frequency cut off) and to various degrees. For all subjects, the residual vision will be characterized by contrast sensitivity and field measurements. Mobility of the subjects is now being tested in an indoor maze of foam rubber columns. The easily randomized maze allows repeated testing under controlled conditions. We will do these experiments at several luminances. Next we will study mobility in three real pedestrian environments: walking on the university campus, on a nature trail, and in a university classroom building. The aim is to determine what measurements of visual capacity will predict mobility performance.